compiler/rustc_infer/src/traits/engine.rs

   1 use crate::infer::InferCtxt;
   2 use crate::traits::Obligation;
   3 use rustc_data_structures::fx::FxHashMap;
   4 use rustc_hir::def_id::DefId;
   5 use rustc_middle::ty::{self, ToPredicate, Ty};
   6
   7 use super::FulfillmentError;
   8 use super::{ObligationCause, PredicateObligation};
   9
  10 pub trait TraitEngine<'tcx>: 'tcx {
  11     /// Requires that `ty` must implement the trait with `def_id` in
  12     /// the given environment. This trait must not have any type
  13     /// parameters (except for `Self`).
  14     fn register_bound(
  15         &mut self,
  16         infcx: &InferCtxt<'tcx>,
  17         param_env: ty::ParamEnv<'tcx>,
  18         ty: Ty<'tcx>,
  19         def_id: DefId,
  20         cause: ObligationCause<'tcx>,
  21     ) {
  22         let trait_ref = infcx.tcx.mk_trait_ref(def_id, [ty]);
  23         self.register_predicate_obligation(
  24             infcx,
  25             Obligation {
  26                 cause,
  27                 recursion_depth: 0,
  28                 param_env,
  29                 predicate: ty::Binder::dummy(trait_ref).without_const().to_predicate(infcx.tcx),
  30             },
  31         );
  32     }
  33
  34     fn register_predicate_obligation(
  35         &mut self,
  36         infcx: &InferCtxt<'tcx>,
  37         obligation: PredicateObligation<'tcx>,
  38     );
  39
  40     fn select_all_or_error(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
  41
  42     fn select_where_possible(&mut self, infcx: &InferCtxt<'tcx>) -> Vec<FulfillmentError<'tcx>>;
  43
  44     fn pending_obligations(&self) -> Vec<PredicateObligation<'tcx>>;
  45
  46     fn relationships(&mut self) -> &mut FxHashMap<ty::TyVid, ty::FoundRelationships>;
  47 }
  48
  49 pub trait TraitEngineExt<'tcx> {
  50     fn register_predicate_obligations(
  51         &mut self,
  52         infcx: &InferCtxt<'tcx>,
  53         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
  54     );
  55 }
  56
  57 impl<'tcx, T: ?Sized + TraitEngine<'tcx>> TraitEngineExt<'tcx> for T {
  58     fn register_predicate_obligations(
  59         &mut self,
  60         infcx: &InferCtxt<'tcx>,
  61         obligations: impl IntoIterator<Item = PredicateObligation<'tcx>>,
  62     ) {
  63         for obligation in obligations {
  64             self.register_predicate_obligation(infcx, obligation);
  65         }
  66     }
  67 }